Distance between floor joists

[Disciple72]

Hello, I'm new to this site and am hoping that the experts on here will be able to help me with this small project that I am about to undertake.

Approximately 5 years ago I had builders in to carryout rather extensive extension works to my property, in this work was a kitchen extension with a small wc/shower room to the side of it. The size of this shower room is 76" x 44", but due to the money running ou,t this part of the project was never finished. We have now decided that it's long overdue and that I will carry out the work to complete this myself. The Shower room is just a block shell with no flooring what so ever at the moment. As you step from the kitchen into the shower room there is approx a 12" drop, so I need to install a floor on the same level as the kitchen.

I basically wanted to ask you experts how I should go about installing this floor. I intend to fix lengths of timber down either side on the length on the room (76") and then span across the width (44") at various intervals.

I intend to use 5"x2" timber to span across the width but would really appreciate any advice initially on what fixings to use to fix the 2 lengths (76") of timber to the block work, how to then fix the joists to these timbers i.e. joist hangers and what distance apart should I fix the joists i.e. 16" centres. I'm obviously putting a shower at the one end of the room using a 1000mm x 700 cast shower base which is rather heavy. Do I need to put the joists closer together under this? What type of flooring would you put on top of the joists, MDF or proper timber floor boards and what thickness would you use. I'll obviously need to know this so that I can fix the joist at the correct height to then take the flooring so that it meets exactly with the kitchen floor.

I know there are quite a lot of questions here, and appreciate that you might not know all the answers, but even if you can give me just one answer or point me in the right direction it would be a real help.

Many thanks in advance and appreciate the time you've taken to read this post.

P.S. I've added the image below of the Shower room as it is now. Please ignore the clutter in there.

Shower Room

• Disciple72
• 23 Apr 2011
• 1

As you can see I've been using the space for storing bits and bobs, but this is where the shower...

 

[bookahandyman]

fixe your two side timbers with suitable plugs and coach bolts or similar every 250mm. then fit cross peices at 400mm centres using medium use joist hangers.
use annular ring shank nails for the hangers. i presume this floor is above the dpc already and more dpc is not req'd if not then you will have to think about that too.

 

[Richard C]

Do you intend to tile this floor?

 

[Disciple72]

fixe your two side timbers with suitable plugs and coach bolts or similar every 250mm. then fit cross peices at 400mm centres using medium use joist hangers.
use annular ring shank nails for the hangers. i presume this floor is above the dpc already and more dpc is not req'd if not then you will have to think about that too.

Thanks for your reply. What size coach bolt do you recommend? Sorry but I don't understand what a medium use joist hanger is, will this take 5"x2". Yes the DPC is all ready in.

 

[Disciple72]

Do you intend to tile this floor?

Hi, thanks for your reply. Yes Im going to tile the kitchen and right through into the shower room all in the same tiles.

 

[Richard C]

You need a rigid floor for tiling; 5 x 2” should be OK as long as you span across the width. Floor must be WBP ply & you should be OK with 18mm but it may be best to go to 22mm. Dint use chipboard, its really not suitable as a tile base. What’s’ the floor in the kitchen made of? How big is it? Tiling through a door opening can be a problem where two floor stuctures meet or if the floors are different materials & you mayneed an expansion joint or at least an uncoupling membrane.

What are you finishing the walls with? Best to use tile backer board in wet areas not PB unless you tank it; but if you’re having large format tiles, you may need a backer board to support the tile weight anyway.

I would read the Tiling Forum sticky & archive posts before you go any further, if you make mistakes with preparation & tiling materials at this stage it will ultimately affect how long your shower room & kitchen floor tiling job will last. By all means come back with further questions in there if you need to.

 

[Disciple72]

You need a rigid floor for tiling; 5 x 2” should be OK as long as you span across the width. Floor must be WBP ply & you should be OK with 18mm but it may be best to go to 22mm. Dint use chipboard, its really not suitable as a tile base. What’s’ the floor in the kitchen made of? How big is it? Tiling through a door opening can be a problem where two floor stuctures meet or if the floors are different materials & you mayneed an expansion joint or at least an uncoupling membrane.

What are you finishing the walls with? Best to use tile backer board in wet areas not PB unless you tank it; but if you’re having large format tiles, you may need a backer board to support the tile weight anyway.

I would read the Tiling Forum sticky & archive posts before you go any further, if you make mistakes with preparation & tiling materials at this stage it will ultimately affect how long your shower room & kitchen floor tiling job will last. By all means come back with further questions in there if you need to.

Brilliant advice Richard and really appreciated. The kitchen floor was all put in when the extension was done, it's a concrete screed and is about 11' x 13'. The shower room I'm working on is added on to the kitchen but is taken off part of the garage which is 12" lower down.

 

[Richard C]

The size of the kitchen floor wont be a problem then but don’t tile straight through the doorway into the shower. Adjoining floors of different construction & materials (concrete & timber) means there will be differential expansion & movement where the two meet, fit an expansion joint where the two meet or the tiles will crack.

Don’t forget, read the Tiling Forum Sticky & archive posts & only use quality trade tiling products of the correct type for your tiles/tile base, the cheap DIY stuff is mostly crap.

 

[Disciple72]

Thanks once again Richard.

 

[Disciple72]

I was hoping thaat someone might be able to point me I the right direction to the joist hangers that I will need. I've been looking at the light duty joist hanger on toolbox.co.uk

http://www.toolstation.com/shop/Structural/Builders+Metalwork/d210/sd2797

 

[bookahandyman]

http://www.toolstation.com/shop/Str...ght+Duty+Joist+Hanger+50mm/d210/sd2797/p59640

item no 59640

coach bolts use something like these

http://www.diy.com/diy/jsp/bq/nav.j...crew&fh_eds=ß&fh_refview=search&isSearch=true

you may need a shorter one depending how thick your wall is.

put a washer it on too, use 10/12mm rawl plugs.

 

[Disciple72]

Superb, much appreciated.